Date: Tue, 21 Apr 2020 22:55:01 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Julien Rouhaud <rjuju123@gmail.com>,
	Kyotaro Horiguchi <horikyota.ntt@gmail.com>,
	Peter Eisentraut <peter.eisentraut@2ndquadrant.com>,
	Dilip Kumar <dilipbalaut@gmail.com>,
	Kuntal Ghosh <kuntalghosh.2007@gmail.com>,
	Fujii Masao <masao.fujii@oss.nttdata.com>,
	Kirill Bychik <kirill.bychik@gmail.com>,
	pgsql-hackers <pgsql-hackers@postgresql.org>,
	Thomas Munro <thomas.munro@gmail.com>
Subject: Re: WAL usage calculation patch
Message-ID: <20200422035501.GN3890@telsasoft.com>
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On Wed, Apr 22, 2020 at 09:15:08AM +0530, Amit Kapila wrote:
> > > > And add the acronym to the docs:
> > > >
> > > > $ git grep 'full page' '*/explain.sgml'
> > > > doc/src/sgml/ref/explain.sgml:      number of records, number of full page writes and amount of WAL bytes
> > > >
> > > > "..full page writes (FPW).."
> > >
> > > Indeed!  Fixed (using lowercase to match current output).
> >
> > I searched through the documentation and AFAICS most of occurances of
> > "full page" are follwed by "image" and full_page_writes is used only
> > as the parameter name.
> >
> > I'm fine with fpw as the acronym, but "fpw means the number of full
> > page images" looks odd..
> >
> 
> I don't understand this.  Where are we using such a description of fpw?

I suggested to add " (FPW)" to the new docs for "explain(wal)"
But, the documentation before this commit mostly refers to "full page images".
So the implication is that maybe we should use that language (and FPI acronym).

The only pre-existing use of "full page writes" seems to be here:
$ git grep -iC2 'full page write' origin doc 
origin:doc/src/sgml/wal.sgml-      Internal data structures such as <filename>pg_xact</filename>, <filename>pg_subtrans</filename>, <filename>pg_multixact</filename>,
origin:doc/src/sgml/wal.sgml-      <filename>pg_serial</filename>, <filename>pg_notify</filename>, <filename>pg_stat</filename>, <filename>pg_snapshots</filename> are not directly
origin:doc/src/sgml/wal.sgml:      checksummed, nor are pages protected by full page writes. However, where

And we're not using either acronym.

-- 
Justin